Access to a station paid area can be controlled by utilization of an array of automatic fare collection (AFC) gates. These automatic fare collection gates are available in several configurations depending on specific transit agency needs, and typically read from and write to one or a combination of fare cards. Fare cards may include contact smart cards, contactless smart cards, and magnetic stripe cards. Full gates with access control typically include a physical barrier, such as a moveable bar, between two console elements. A fully gated system ensures, for all practical purposes, that fares are purchased by each patron. However, fully gated systems present disadvantages to a busy station as patrons are required to file through the gates one by one. In addition, installation and maintenance of these gates are costly.
An alternative to full gates are stand alone validators (SAV) that are used in proof-of-payment systems. A stand alone validator validates passes and tickets held by patrons, in uncontrolled areas accessible by all, but supposedly, only by patrons who have paid for the transportation or access. Transit agencies employ such techniques because the costs for a fully controlled access area are higher than they are able or willing to pay. The disadvantage of proof-of-payment systems is that, without controlled access, there is a high incidence of unpaid users of the system. The generation of any revenue is dependent upon the honesty of customers and the spot checking performed by transit agency personnel, who sometime may use a hand held verifier. Transit agencies that have installed gated systems have significantly reduced loss due to theft, human error, transfer fraud, and fare evasion. As transit ridership grows, it becomes more and more difficult to rely on policing to ensure payment within proof-of-payment systems.